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Battery keeps draining even after replacing alternator on 94 gcl 5.2 any ideas

I have replaced alternator checked all fuses and alarm system and still have slow drain on battery --battery is new also. it usually takes about 1-2 days and battery is dead any ideas?

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  • Jeep Master
  • 78,267 Answers

Try this, disconnect the alternator and see if it still drains the alternator, you say new but i know it is rebuilt, and some rebuilders do a terrible job, this is esp true of the so called discount auto parts stores (that is a joke as they often charge more than a dealer) such as O'reilly and others. Buy a Mopar rebuilt if the alternator turns out to be the source of the battery draw down. Also make sure no light inside the truck are on like sun visor lights and so on. Have the battery tested shorted cells cause a draw and will kill the battery overnight, don't over testing new parts as they can be bad, found this out the hard way early in my mechanical career.

Posted on Nov 01, 2012


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Do you have any stereo equip? Amps? Subs? Aftermarket CD player?

Posted on Dec 19, 2008

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SOURCE: slow to fast battery drain problem when engine is off.

If you connect a 12VDC test light in line, between your + battery post & + battery cable,(cable off battery obviously) the light will stay lit brightly as long as there is a draw. Keep in mind your radio will cause some due to memory function, clock etc. Pull stereo/radio fuse to eliminate that draw, then start removing fuses, and putting them back, watch light. If it dims, or goes out, you've found the source of your current draw. I have had to resort to pulling them all,(after making notes for anything I needed to remember about where they were) to get light to go out, then re-installing one by one & watching light. When it comes on nice & bright, note which fuse slot, and pull it back out and continue on, in case of more than one draw.

Posted on Mar 01, 2009

Mr BrokRench
  • 1623 Answers

SOURCE: 2000 Navigator - something draining on battery - goes dead

Hellokrissypoo4...Your navigator has what is known as a parasitic battery drain...meaning, something in the vehicles system is not turning is the way i test for this, you will need a digitial multimeter to perform this test...when doing this test make sure that the dome light, under hood light, trunk light, etc. are OFF.

  1. Remove the negative side battery cable from the negative battery terminal.
  2. Attach an ammeter(this measures amperage) between the negative cable and the negative battery post. wait a few seconds to several minutes for the car to go into sleep mode. i.e. when you make the contact with the test light the cars computer systems "wake up" after a bit of time they will go to "sleep".
  3. If the ammeter is reading over 25-50 milliamps, something is using too much battery power.
  4. Go to the fuse panel(s) and remove fuses, one at a time. Pull the main fuses (higher amp ratings)last. Be sure to observe the ammeter after pulling each fuse.
  5. Watch for the ammeter to drop to acceptable drain. The fuse that reduces the drain is the draw. Consult the owners' manual or service manual to find what circuits are on that fuse.
  6. Check each device (circuit) on that fuse. Stop each lamp, heater, etc. to find the drain.
  7. Repeat steps 1&2 to test your repair. The ammeter will tell you exact numbers

  8. Some after-market alarm systems may make this test too long or loud to be worth the effort. If that's the case, seek professional help.
  9. In more and more models made after 2003 disconnecting the battery will reset the PCM requiring the modules to relearn. In certain cases this requires a factory scan tool. It is best to take such cars to either the dealer or a professional in auto electrical systems.
  10. Be careful working around the battery in a car
Good luck krissy..i hope this helps..please rate me a fixya.

Posted on Jul 22, 2009

  • 491 Answers

SOURCE: 2005 Dodge Caravan with Dead Battery. Replaced

Disconnect battery from vehicle overnight to check for internal battery drain.......just take one of the cables off.
If the battery is still up and starting the vehicle after being disconnected after a day or two......the drain IS in the vehicle and will have to be checked again.
Do it yourself.
Buy a cheap 12 volt test light.
Place it between the cable you removed before.
One end on the battery post and the other on the cable end.
Now....with the key off......
If the light glows have TOO MUCH drain.
We want a dim glowing light.
The dim light is just the memory circuits in the electronics and OK.

With the doors closed....take out one fuse at a time until the light glows dim.......the fuse that dims the light is the problem circuit.
If no fuse dims the light...remove relays one at a time.
Remember....some fuses and relays could be in the engine compartment and under the dash.
If no relay dims the light disconnect ALL alternator wires.
Remember....anything that uses power will make the light glow ....keep those doors closed (we do not want interior light drain affecting the test ) and if you have a under hood light check it first by removing the bulb.
We do not want false readings.

Posted on Sep 22, 2009

  • 580 Answers

SOURCE: 2003 Ford Focus battery light is on, but alternator appears good

Disconnect battery ground for 30 seconds & reconnect. Light should be out unless you have deeper diagnostic problem. Charging system good Battery good. This action should reset trouble light. Good luck!

Posted on Dec 29, 2009

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3 Answers

What is the most battery draining part when car sits over night

hi Larue.
You're late for work and rush out to your car, only to find that it won't start. The headlights are dim and the engine simply refuses to turn over. You realize that your battery is dead. But how did this happen? There are five main causes of car battery drain or failure.

Human error

You've probably done this at least once in your life - you come home from work, tired and not really thinking, and left the headlights on or didn't completely close the trunk. Overnight the battery drains, and in the morning your car won't start. Many new cars alert you if you've left your lights on, but may not have alerts for other components.

Parasitic drain

Parasitic drain is due to components in your vehicle continuing to run after the key is turned off. Some parasitic drain is normal - your battery delivers enough energy to keep things, like your clock, radio presets, and security alarm operational at all times. However, if there's an electrical problem, parasitic drain can exceed what's normal and deplete the battery.

Bad charging

If your charging system isn't working properly, your car battery can drain even while you're driving. Many cars power their lights, radio, and other systems from the alternator, which can make the battery drain worse if there's a charging problem. Then you'll be stranded at roadside with a stalled car that needs a boost. And even then, bad charging will drain your car's battery. A professional mechanic will be able to diagnose what's causing a charging problem.

Defective alternator diode

A car alternator recharges the battery and powers certain electrical systems. If your alternator has a bad diode, your battery can drain. The bad diode can cause the circuit to charge even when the engine is shut off, and you end up in the morning with a car that won't start.

Old battery

If your battery is old, it might not hold a full charge. If your car consistently won't start, it's possible that the battery is worn out. You should generally replace your car battery every 4-5 years. If your car isn't starting consistently, and your battery is old, battery replacement should be the first thing you consider.
Having a battery that won't hold a charge is frustrating, and figuring out what's causing the problem can be tricky. Assuming that the cause of the battery drain is not human error, you will need the assistance of a qualified mechanic who can diagnose your car's electrical problemsand determine if it is the battery or something else in the electrical system.
you can read up some more at this link.

What is the most battery draining part when car sits over night Google...

Dec 17, 2017 | Cars & Trucks

1 Answer

Battery keeps drainging

Try disconnecting the alternator leads overnight but make sure they are kept away from the body, the big cable is always HOT. See if that does it overnight. If its OK then the alts duff. If not then get a small tester / amp meter set up and connect it between the neg post and the neg lead. This will give you some idea of the drain in amps. With the car locked as normal remove and replace the fuses to lights,door locks etc until the ammeter suddenly reads zero. Then you have an idea of which item is draining it. Door locks are an old favourite after the alternator. Alternators can back drain a batt even if they show a charge when running. Get a pal with electrical knowledge to help.

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My 94 montero keeps draining battery. the battery and alternator is good. i can drive it , but the battery gauge gets lower and it drains completly. the 4wheel drive indicator light starts flashing right...

You say the alternator is good, but it sounds like it is not charging the battery. Have you had the charging system tested on the truck ?
Could be the main fuse for the alternator. Its usually large, 80 or 100 amp in size.

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Sounds like you have a short in your alarm or on the Positive battery cable that is grounding your battery and draining it. If this has happened more than once on this battery get a battery cell tester and test the battery cells to make sure you have developed a dead cell which will happen. When you jump the vehicle take the positive battery cable off the battery. If the vehicle continues to run the Alternator is working properly if it dies, which explains why you jump it and have to re-jump it again after driving it, the alternator or voltage regulator is malfunctioning. If you have installed a power amplifier in the vehicle that has cabling under the hood double check that for shorts and check you power wires at the ignition switch for a short.

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1 Answer

Can the security alarm of a car shut down the battery or alternator? Can the security system drain the battery constantly? Just had the battery and alternator replaced. This is a 1999 Ford Windstar Mini...

If there is an alarm that sounding 24 hrs a day, yes, it can drain your battery.
I can't go by what somebody else said or didn't say. I can't go by what was or wasn't replaced. If you replace a component and the wiring circuit is faulty, it still won't work, even if the part is new. By the way, I'm not a fan of rebuilt parts. If you want to do some testing, I will try to help, but, you have to do the testing. Use a digital multimeter across battery posts, if you don't have one, get one. With the meter on, engine off, place leads across battery posts, The generic spec for a full charge is 12.6 volts, if battery is down, get it charged or we're just spinning our wheels. Usually the digital multimeter has a 10 amp setting, where you can check battery amp draw with everything off, On that setting you use the meter in series with one of your battery cables, engine off. A generic amp draw spec is around 50 ma, that is .050 not even a tenth of an amp. If the reading is very high, check for lights left on, interior--under the hood, where ever. Best time to check is in the dark. If that is ok, pull/replace fuses one at a time, when you pull the fuse on problem circuit, the drain returns to normal. Then you check everything on that fuse circuit to find the problem. If you want to check charging system, begin by checking for charging system trouble codes. Some of the national brand auto stores will check codes for free, if there are any. I don't know if they will check manufacturer specific codes? You can get an obd2 code reader. Your computer has control over charging system. Also, you can see fuses and fusible links. Check the basics before worrying about the pcm. Just my opinion.
windstar generator-vt2ux1gi52dp2r4gy4y0zpkn-1-0.jpg

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1 Answer

I have 1989 300e mercedes. If i drive and let sit overnight it will not start. Battery dead. I replaced the battery and alternator. If i charge battery for less than 5 minutes it will crank and start up....

Do the fans run properly and shut off when cars is off? If not they may be draining the battery. A bad stock antenna could drain battery because of the control module. Also the central locking pump if it keeps running (its supposed to shut off after 30 seconds) but if it fails it will drain the battery.

Disconnect each system 1 by 1 or pull fuses 1 by 1 to find out. I would believe its your neutral safety switch tho. Its on the transmission.

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Before you disable your alarm try this, disconnect the alternator field plug over night, check battery voltage at the battery before you disconnect the plug then disconnect and leave alone over night, make sure you have at least 12 volts when you disconnect the alt.
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I suspect you may have a leaking diode in your alternator's internal regulator, have seen it many times on your model... Certainly worth a try. Let me know how it turns out....

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